1. Technical Field
The disclosure relates to display technology. More particularly, the disclosure relates to a display device, an array substrate, and a thin film transistor thereof.
2. Description of Related Art
One important specification of a planar display device is brightness, and the most important determining factor of the brightness is aperture ratio. Aperture ratio is a ratio of the effective area that light can pass through. Therefore, the more the aperture ratio is, the brighter the brightness of the display device is. One important affecting factor of the aperture ratio is the area occupied by a thin film transistor (TFT) of each pixel.
The present TFT technology horizontally disposes the gate, the semiconductor layer, the source and the drain on a substrate. Moreover, an opaque layer is disposed on the TFT to prevent the TFT from generating photocurrent, which can produce a current leakage problem. Therefore, the area occupied by the TFT in each pixel cannot transmit light, and the brightness of the display device is thus limited. That means, the more the area occupied by the TFT is, the smaller the aperture ratio is, and the lower the brightness of the display device is.
However, if the TFT performance is increased, for example, by increasing the width of the source and the drain to increase the current of the TFT to achieve a quicker charging and discharging rate, the area occupied by the TFT is increased, too. Then, the aperture ratio is further decreased.
At present, the size of the TFT can be significantly decreased after the discovery of metal oxide semiconductor material. However, the TFT still occupy relatively large pixel area.